Locking wrenches are well known tools that are employed in situations where it is desirable to clamp one structural member to another so that the operator's hands may be freed to accomplish other tasks. Examples of conventional locking wrenches include those wrenches disclosed in prior-issued U.S. Pat. Nos. 2,280,005 issued to William Peterson on Apr. 14, 1942; U.S. Pat. No. 2,514,130 issued to Harold T. Jones on Jul. 4, 1950; and U.S. Pat. No. 2,592,807 issued to Harold T. Jones on Apr. 15, 1952 (the entire content of each of these prior-issued U.S. Patents being expressly incorporated hereinto by reference).
Conventional locking wrenches are generally comprised of an upper handle having a fixed-position upper jaw at its forward end and a threaded sleeve at its rearward end. A pivotally movable lower jaw is disposed in opposition to the upper jaw and is moved towards and away from the upper jaw by means of a lower operating handle (which is itself pivotally connected to the lower jaw). A toggle lever is pivotally connected at one end to the lower operating handle, and is slidably received within the upper handle at its opposite end. Typically, a tension spring biases the lower jaw in a pivotal direction tending to separate it from the upper jaw. An adjustment screw is threadably coupled within the sleeve of the upper handle and has a terminal end that acts upon the opposite end of the toggle lever.
As those in the art will appreciate, due to the relative connections between the toggle lever, lower operating handle, and lower jaw, turning movements applied to the adjustment screw will responsively cause the lower jaw to be moved pivotally relative to the fixed upper jaw. In this manner, the clamping force that is exerted by the upper and lower jaws may be selectively adjusted by the operator. In addition, the toggle lever increases the clamping force that is applied to structural members held between the upper and lower jaws when the lower operating handle is forcibly moved into a closed condition relative to the upper handle.
While conventional clamping wrenches function to clamp structural members securely one to another, there is a risk that the clamping force may suddenly be released--e.g., as might occur should the wrench and/or structural members held by the wrench be struck by an object with sufficient force to cause the lower operating handle to be moved under the influence of the tension spring to an opened condition relative to the upper handle. Sudden releases of the clamping force may, int urn, release the structural members that had just moments before been securely clamped and allow them to strike the operator and/or others in the vicinity of the work area thereby causing potentially serious injuries.
One prior proposal for positionally retraining the upper and lower handles of a locking wrench is represented by U.S. Pat. No. 4,889,021 issued to Joseph L. to Morrison on Dec. 26, 1989. According to Morrison '021, the upper and lower handles of a locking wrench are provided with vertically aligned apertures so as to accomodate upper and lower stubs associated with an especially adapted padlock. The upper stub moreover bears against a brake means located physically within the upper handle member so as to apply braking force against the adjustment screw thereby inhibiting its turning movements.
While the locking wrench proposal in Morrison '021 appears to function in a manner that would minimize the risk of sudden release of the clamping force, it necessarily requires a separate and especially adapted padlock to always be available to the operator.
What has been needed therefore are improvements to conventional locking-type wrenches which would significantly reduce (if not eliminate entirely) the risks associated with the inadvertent sudden release of a wrench's clamping force and which would not require especially adapted restraining elements. Thus, locking-type wrenches that are inherently safer and more convenient to use have been needed. It is towards fulfilling such needs that the present invention is directed.
According to the present invention, novel locking-type wrenches are provided such that the upper and lower handles are positionally restrained or immobilized relative to one another. More specifically, preferred embodiments of the present invention include a rearwardly directed extension member that defines an aperture associated with the lower operating handle, and means associated with the adjustment screw to coact with the aperture in the lower handle flange extension so as to positionally restrain the upper and lower handles relative to one another.
According to some preferred embodiments of the present invention, the head of the adjustment screw includes pairs of radially extending wings each of which defines an opening. The extension member is rigid with the lower operating handle and is located at a position such that it may be brought into an adjacent position with one of the wings when the lower operating handle is in a closed condition relative to the upper handle. Thus, when the extension member is adjacently positioned relative to one of the wings (i.e., when the lower operating handle is in a closed condition), the respective opening defined in that one wing and the aperture defined in the extension member will be in alignment. In such a manner, a restraining element (which could be virtually any suitable rigid or flexible member, such as a bolt, pin, rod, tube, padlock hasp, wire, rope, or the like) may be passed through the aligned opening/aperture to thereby positionally restrain the upper and lower handle members relative to one another. The risk of inadvertent sudden release of the clamping force is thereby minimized (if not eliminated).
Other embodiments of the invention include apertured adjustment screw heads of selected geometrical configuration, and an opening defined in the extension member. The extension member according to these alternative embodiments will likewise be oriented so that it is adjacent to the apertured adjustment screw head when the lower operating handle member is in its closed condition so that at least one of its defined apertures will be in alignment with an opening formed in the extension member.
The handle-restraining systems of this invention may also include an integral locking assembly provided operatively with the adjustment screw and the lower operating handle so that the respective restraining elements may be coupled structurally one to another to thereby physically restrain the lower operating handle relative to the upper handle. Thus, the extension member may include a movable restraining element that defines an opening. The restraining element may be pivoted, for example, so that its defined opening is brought into operative association with a key flange associated with the adjustment screw head so as to positionally restrain the upper and lower operating handles when in their closed condition. Alternatively, the handle-restraining system may be embodied in generally U-shaped open channels on the terminal ends of the wings radially extending from the adjustment screw so as to accept a portion of the flange extension associated with the lower operating handle and thereby provide a greater measure against inadvertent separation of the upper and lower handles.
The locking assembly of this invention may also be embodied in a spring-biased locking button associated with the head of the adjustment screw which is adapted to coact with the aperture defined in the extension flange of the lower handle and thereby positionally lock the lower and upper handles one to another. Furthermore, positional locking may be achieved by providing a movable locking member on the extension flange of the lower operating handle which is adapted to be moved into locked and unlocked conditions with respect to one of the openings defined in the adjustment screw when the lower handle is in its closed state.
The extension flange of the lower operating handle will move axially substantially in unison with axial movements of the adjustment screw between greater and lesser positions due to the manner in which the lower operating handle is connected operably to the adjustment screw. As a result, the restraining elements associated with the adjustment screw and the lower operating handle may reliably be brought into alignment with one another when the lower handle is moved to its closed condition. Thus, the handle-restraining systems of this invention allow for positional restraint of the lower and upper handles to be achieved over substantially the entire range of operation of the adjustment screw (and thereby substantially the entire range of clamping forces achievable by the wrench).
Further aspects and advantages of this invention will become more clear after careful consideration is give to the following detailed description of the preferred exemplary embodiments thereof.